There is no excretory mechanism for iron. Iron will correct only hemoglobin abnormalities due to iron deficiency and should not be used to treat conditions such as thalassemia, hemosiderosis, hemochromatosis, normocytic anemia (unless iron deficiency exists), or in patients receiving blood transfusions. Clinical monitoring of erythropoietic function and ferritin levels is recommended.

Folic acid (Includes ferrous fumarate/folic acid) ↔ anemia

The use of folic acid is contraindicated in patients with undiagnosed anemia. Folic acid in dosages above 1 mg/day can obscure the diagnosis of pernicious anemia by alleviating the hematologic abnormalities while allowing the progression of neurologic complications. In addition, folic acid alone is improper therapy in the treatment of pernicious anemia and other megaloblastic anemias where vitamin B12 is deficient.

Ferrous salts (Includes ferrous fumarate/folic acid) ↔ achlorhydria

Gastric acidity increases iron bioavailability by maintaining the ingested iron in a reduced form as ferrous ions, which are more readily absorbed than ferric ions. Therefore, when iron therapy is administered orally, higher dosages may be necessary for patients with decreased gastric acid production. Also, a liquid formulation is recommended in these patients because dissolution of the tablet coating depends on normal gastric acidity.